Pneumatic punch press



March 10, 1970 M. JOSEPH 3,499,369

PNEUMATIC PUNCH PRESS Filed Jan. 24, 19es I s 5/ 4 S 24- 2 l g 22 20r-4 i 2 United States Patent Int. Cl. Fb 15/26; Flllb 31/00; F16j 1/10 I US. Cl. 92--16 7 Claims ABSTRACT OF THE DISCLOSURE In a punch press with accelerated piston are provided a main cylinder in which moves an anvil, a secondary cylinder coaxial with the first and positioned in an extension of the first cylinder, and a piston frictionally sliding in at least a part of the secondary cylinder, there being a channel connecting the main cylinder to the secondary cylinder through an adjustable narrowed section, so that when the pressure in the secondary cylinder is suflicient for moving the piston against the frictional force retaining it in the secondary cylinder, the piston leaves the secondary cylinder thus placing the two cylinders in communication with the result that the piston suddenly subjected to the pressure existing in the main cylinder is accelerated and strikes the anvil.

The present invention has for its object a pneumatic punch press with accelerated piston.

Such tools are particularly suitable for working metals. It is also possible to work with them other materials such as synthetic materials and leather. It is possible to perform such work as riveting, folding, punching, stamping, etc.

Punch presses known to this day function with the aid of a spring which must be manually or pneumatically tensed. The impact or the blow is then obtained by the abrupt freeing of the spring which transmits its energy to the tool. Such presses are constituted by a relatively high number of parts which are subjected to excessive wear. Owing to their shape, these presses are bulky and cannot always be used in certain places where the. available room is reduced as is the case in processing machines. Furthermore, the range of their utilization is limited.

In other known pneumatic presses, the piston actuating the tool is directly urged by compressed air entering in the cylinder through a control valve. The speed and the power of this piston are then dependent upon the rapidity with which air penetrates in the cylinder. Such presses are of simple and robust construction, but cannot, owing to their design, be used except for work requiring rather low striking power.

The invention has for its object to provide a pneumatic punch press which is simple to construct, very efficient and may be adjusted.

The accompanying drawing represents by way of example one embodiment of the invention.

In the single figure of the drawing, 1 designates the upper flange of a pneumatic press with its feed conduit 5. The lower flange 2 is connected to the upper flange by a removable tight tube 3 defining a main cylinder 4 in which moves a main piston 6 guided by a ring 16. The main piston is also secured to a tool-holding rod 21 constituted by a cylindrical part.

Above main cylinder 4 and in flange 1 is made a secondary cylinder 8 having a cylindrical seat in which operates a striking piston 11 connected to a striking piece 14. Piston 11 additionally carries a joint 12 which maintains this piston in its seat 25 by friction and ensures the watertightness of the secondary cylinder 8.

3,499,369 Patented Mar. 10, 1970 ice The secondary cylinder communicates with the main cylinder through a channel 7 having an adjustable width owing to the presence of a centre point or metering valve 10 controlled by a screw 9.

The return of piston 6 is ensured by compressed air entering through opening 24. Packing joints 15, 17 and 22 are provided. The rod of the main piston is guided by a socket 20. The air contained in the bore of the main piston 6 may be evacuated through orifice 23.

The pneumatic press operates in the following manner:

When compressed air penetrates at 5 in main cylinder 4. it pushes piston 6 which acts on the piece to be worked through the tool (not shown) located at the extremity of rod 21. The piece to be worked is thus held, driven or centred. Compressed air fills the main cylinder 4 and flows through the connecting channel 7 in the secondary cyliner 8 at a speed varying with the cross section of the. narrow section of this channel. When the pressure in the secondary cylinder or pressure build-up chamber becomes suflicient, it breaks loose the striking piston 11/14 from its frictional engagement with the seat 25. Pison 11 then leaves its seat putting in direct communication the two cylinders in such a way that the. compressed air in cylinder 4 acts in single blow on the striking piston which violently strikes anvil 18 which then transmits this energy to the tool through the agency of rod 19. Piston 11/14 is guided in its movement outside seat 25 by a guiding rod 13.

By means of centre point 10 it is thus possible to adjust the time interval which elapses from the instant when the main piston has reached its lower point and the triggering of thestriking piston.

It is in particular possible to completely close the narrow section of channel 7, the press then working as an ordinary press, that is to say that only the main piston functions, the second piston remaining in its seat since no pressure has arisen to free it therefrom.

What is claimed is:

1. A fluid motor comprising: a cylinder having fluid supply and exhaust ports therein; a main piston slidably mounted in said cylinder for movement in response to fluid pressure applied on one side thereof; a hollow piston rod connected to said main piston and slidably mounted for extension out of and retraction into one end of said cylinder; an anvil slidably mounted within said hollow piston rod; means defining an open-ended pressure build- .up chamber in communication with said supply port in the other end of said cylinder; an impact piston slidably mounted within said cylinder for impacting with said anvil during a working stroke and movement relative to said main piston; holding means for releasably holding said impact piston over said open-ended pressure buildup chamber; and means including said fluid supply and exhaust ports and said cylinder receptive of fluid under pressure for simultaneously driving said main piston to effect extension of said hollow piston rod outwardly of said cylinder to hold a workpiece in place and build up fluid pressure in said pressure build-up chamber to break away said impact piston from said holding means to initiate said working stroke.

2. A fluid motor according to claim 1; wherein said impact piston is slidably mounted in a bore within said main piston; and wherein said impact piston, said main piston, and said anvil are all coaxial.

3. A fluid motor according to claim 2; including a passageway in the rod end of said main piston communicating said cylinder with said bore for exhausting fluid from said bore during said working stroke of said impact piston.

4. A fluid motor according to claim 3; wherein said holding means comprises a friction fit between said impact piston and a wall portion of said pressure build-up chamber.

5. A fluid motor according to claim 1; wherein said last-mentioned means includes a passageway interconnecting said cylinder with said pressure build-up chamber, and a variably settable metering valve positioned within said passageway.

6. A fluid motor according to claim 1; wherein said holding means comprises a friction fit between said impact piston and a wall portion of said pressure buildup chamber.

'7. A fluid motor according to claim 1; wherein said impact piston has a longitudinal bore therein; and a guide rod fixedly connected to said other end of said cylinder and slidably extending into said longitudinal bore to guide the movement of said impact piston during said working stroke.

9/1871 Cooper 9126 8/1932 Smickle 92-65 X 5/1938 Merenda 9262 X 1/ 1957 Kraujalis 9265 X 4/1961 Taber 92-65 X 4/ 1966 Aslan 91-26 11/1968 Kirk 9126 MARTIN P. SCHWADRON, Primary Examiner IRWIN C. COHEN, Assistant Examiner US. Cl. X.R. 

